U.S. patent application number 15/919561 was filed with the patent office on 2018-12-20 for electron beam apparatus, and x-ray generation apparatus and scanning electron microscope each including the same.
This patent application is currently assigned to Shimadzu Corporation. The applicant listed for this patent is Shimadzu Corporation. Invention is credited to Akihiro MIYAOKA.
Application Number | 20180366294 15/919561 |
Document ID | / |
Family ID | 64657592 |
Filed Date | 2018-12-20 |
United States Patent
Application |
20180366294 |
Kind Code |
A1 |
MIYAOKA; Akihiro |
December 20, 2018 |
ELECTRON BEAM APPARATUS, AND X-RAY GENERATION APPARATUS AND
SCANNING ELECTRON MICROSCOPE EACH INCLUDING THE SAME
Abstract
An electron beam apparatus includes: a cathode configured to
emit electrons; an anode that is an electrode which forms an
electric field such that an electron beam is formed by the
electrons emitted from the cathode, and that is formed with a first
hole through which the electron beam passes; an aperture member
formed with an opening that shades a part of the electron beam
which passes through the anode; and a convergence electrode that is
an electrode which forms an electric field such that the electron
beam which passes through the opening converges, and that is
configured to include one single-hole electrode formed with a
second hole through which the electron beam passes.
Inventors: |
MIYAOKA; Akihiro; (Kyoto,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shimadzu Corporation |
Kyoto |
|
JP |
|
|
Assignee: |
Shimadzu Corporation
Kyoto
JP
|
Family ID: |
64657592 |
Appl. No.: |
15/919561 |
Filed: |
March 13, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 2237/06308
20130101; H01J 35/066 20190501; H01J 37/12 20130101; H01J 37/075
20130101; H01J 35/14 20130101; H01J 3/07 20130101; H01J 37/28
20130101; H01J 3/024 20130101; H01J 2237/063 20130101; H01J 35/147
20190501 |
International
Class: |
H01J 3/07 20060101
H01J003/07; H01J 37/075 20060101 H01J037/075; H01J 35/14 20060101
H01J035/14; H01J 3/02 20060101 H01J003/02; H01J 37/12 20060101
H01J037/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2017 |
JP |
2017-118599 |
Claims
1. An electron beam apparatus comprising: a cathode configured to
emit electrons; an anode that is an electrode which forms an
electric field such that an electron beam is formed by the
electrons emitted from the cathode, and that is formed with a first
hole through which the electron beam passes; an aperture member
formed with an opening that shields a part of the electron beam
which passes through the anode; and a final-stage electron lens
that is an electrode which forms an electric field such that the
electron beam which passes through the opening converges, and that
is configured to include one single-hole electrode formed with a
second hole through which the electron beam passes.
2. The electron beam apparatus according to claim 1, wherein an
electric potential of the aperture member is the same as an
electric potential of the single-hole electrode.
3. The electron beam apparatus according to claim 2, further
comprising: a first electrically-conducting member in which the
aperture member and the single-hole electrode are electrically
conducted to each other in vacuum, and which is different from a
wire configured to apply the electric potential.
4. The electron beam apparatus according to claim 3, wherein an
electric potential of the anode is the same as the electric
potential of the aperture member.
5. The electron beam apparatus according to claim 4, further
comprising: a second electrically-conducting member in which the
anode is electrically conducted to the aperture member in vacuum,
and which is different from the wire configured to apply the
electric potential.
6. The electron beam apparatus according to claim 1, wherein a
distance between the aperture member and the single-hole electrode
in a direction along an optical axis of the electron beam is longer
than a radius of the second hole.
7. The electron beam apparatus according to claim 1, wherein the
cathode includes an emission surface which is a planar surface
capable of emitting the electrons, and an area of the emission
surface is larger than an opening area of the first hole.
8. The electron beam apparatus according to claim 1, wherein the
cathode is a thermionic electron emission type.
9. An X-ray generation apparatus comprising the electron beam
apparatus according to claim 1.
10. A scanning electron microscope comprising the electron beam
apparatus according to claim 1.
Description
FIELD
[0001] The present invention relates to an electron beam apparatus,
and an X-ray generation apparatus and a scanning electron
microscope each including the same.
BACKGROUND
[0002] In an electron beam apparatus, which is used for a scanning
electron microscope, an X-ray generation apparatus, or the like, an
electro-magnetic lens and an electro-static lens are used as an
electron lens which causes an electron beam to converge. Generally,
it is easy to reduce a size of the electro-static lens, compared to
the electro-magnetic lens. In a scanning electron microscope
disclosed in Patent Literature 1, a size of the electron beam
apparatus is reduced in such a way that an electron gun lens and an
object lens are respectively used as the electro-static lens.
[0003] [Patent Literature 1] JP-A-6-111745
SUMMARY
[0004] The electron beam apparatus is mounted on various machines
including the X-ray generation apparatus and the scanning electron
microscope. With such a background, it is desired to further reduce
the size of the electron beam apparatus itself.
[0005] An object of the present invention is to provide a
small-sized high-resolution electron beam apparatus, and an X-ray
generation apparatus and a scanning electron microscope each
including the same.
[0006] According to an aspect of the present invention, there is
provided an electron beam apparatus including: a cathode configured
to emit electrons; an anode that is an electrode which forms an
electric field such that an electron beam is formed by the
electrons emitted from the cathode, and that is formed with a first
hole through which the electron beam passes; an aperture member
formed with an opening that shields a part of the electron beam
which passes through the anode; and a final-stage electron lens
that is an electrode which forms an electric field such that the
electron beam which passes through the opening converges, and that
is configured to include one single-hole electrode formed with a
second hole through which the electron beam passes.
[0007] According to the configuration, the final-stage electron
lens, which forms the electric field such that the electron beam
converges, includes one single-hole electrode. Therefore, it is
possible to reduce a size compared to, for example, a case where
the electron lens includes a plurality of single-hole electrodes
like an einzel lens. Therefore, it is possible to reduce a size of
the electron beam apparatus.
[0008] In addition, according to the configuration, the aperture
member shields the electron beam at a peripheral part of the
electron beam which has a bad converging property, only the central
part of the electron beam which has a good converging property
passes through the opening of the aperture member, and, thereafter,
the electron beam converges by the final-stage electron lens.
Therefore, it is possible to suppress degradation of
resolution.
[0009] According to an example of the electron beam apparatus, an
electric potential of the aperture member is the same as an
electric potential of the single-hole electrode.
[0010] According to the configuration, it is not necessary to
provide an insulation distance in order to prevent electric
discharge between the single-hole electrode and the aperture
member. Therefore, it is possible to reduce a distance between the
single-hole electrode and the aperture member. Therefore, it is
possible to reduce a size of the electron beam apparatus.
[0011] According to an example of the electron beam apparatus, as a
method for applying the same electric potential, a first
electrically-conducting member is further included in which the
aperture member and the single-hole electrode are electrically
conducted to each other in vacuum, and which is different from a
wire configured to apply the electric potential.
[0012] According to the configuration, it is possible to apply the
electric potential to both the single-hole electrode and the
aperture member via one wire, with the result that it is possible
to reduce the number of wires, and thus it is possible to simplify
a configuration of the electron beam apparatus.
[0013] According to an example of the electron beam apparatus, an
electric potential of the anode is the same as the electric
potential of the aperture member.
[0014] According to the configuration, it is not necessary to
provide an insulation distance in order to prevent the electric
discharge between the anode and the aperture member. Therefore, it
is possible to reduce the distance between the anode and the
aperture member. Therefore, it is possible to reduce a size of the
electron beam apparatus.
[0015] According to an example of the electron beam apparatus, as
the method for applying the same electric potential, a second
electrically-conducting member is included in which the anode and
the aperture member are electrically conducted to each other in
vacuum, and which is different from the wire configured to apply
the electric potential.
[0016] According to the configuration, it is possible to apply the
electric potential to both the anode and the aperture member via
one wire, with the result that it is possible to reduce the number
of wires, and thus it is possible to simplify the configuration of
the electron beam apparatus.
[0017] According to an example of the electron beam apparatus, a
distance between the aperture member and the single-hole electrode
in a direction along an optical axis of the electron beam is longer
than a radius of the second hole.
[0018] According to the configuration, it is possible to ignore an
operation of the electro-static lens due to the aperture member.
Therefore, it is possible to design an opening diameter of the
aperture member without taking the operation of the lens into
consideration.
[0019] According to an example of the electron beam apparatus, the
cathode includes an emission surface which is a planar surface
capable of emitting the electrons, and an area of the emission
surface is larger than an opening area of the first hole.
[0020] According to the configuration, for example, compared to a
case where the cathode is formed of pointed metal, it is not
necessary to perform high-precision adjustment on a position of the
cathode with respect to the first hole, and thus it is possible to
easily construct the electron beam apparatus.
[0021] According to an example of the electron beam apparatus, the
cathode is a thermionic electron emission type.
[0022] According to the configuration, for example, compared to a
configuration which includes an electric field emission-type
cathode, a degree of vacuum in the electron beam apparatus may be
low. Therefore, it is possible to reduce a size of a vacuum pump
used to vacuate an inside of the electron beam apparatus.
[0023] According to the present invention, an X-ray generation
apparatus includes the electron beam apparatus.
[0024] According to the present invention, a scanning electron
microscope includes the electron beam apparatus.
[0025] According to the present invention, it is possible to
provide a small-sized high-resolution electron beam apparatus, and
an X-ray generation apparatus and a scanning electron microscope
each including the same.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic configuration diagram illustrating one
embodiment of an electron beam apparatus;
[0027] FIG. 2 is an enlarged diagram illustrating a convergence
electrode of FIG. 1 and peripheries thereof;
[0028] FIG. 3 is an enlarged diagram illustrating a convergence
electrode according to a comparative example and peripheries
thereof;
[0029] FIG. 4 is a schematic configuration diagram illustrating a
part of an electron beam apparatus according to a modified
example;
[0030] FIG. 5 is a schematic configuration diagram illustrating a
part of the electron beam apparatus according to the modified
example; and
[0031] FIG. 6 is a schematic configuration diagram illustrating a
part of the electron beam apparatus according to the modified
example.
DETAILED DESCRIPTION OF THE DRAWINGS
[0032] As illustrated in FIG. 1, an electron beam apparatus 1
includes a vacuum chamber 10 whose inside becomes a vacuum state by
a vacuum pump (not shown in the drawing), an electron gun 20 which
is placed in the vacuum chamber 10, an aperture member 30, and a
convergence electrode 40. The electron beam apparatus 1 further
includes a control device 60 which electrifies the electron gun 20,
the aperture member 30, the convergence electrode 40, and a target
object 50. The electron beam apparatus 1 causes an electron beam
emitted from the electron gun 20 to pass through the aperture
member 30, causes the electron beam to converge by the convergence
electrode 40 after shielding peripheral parts of the electron beam,
and causes a convergence surface 51, which is a surface of the
target object 50, to be irradiated with the electron beam. The
electron beam apparatus 1 is used for, for example, an X-ray
generation apparatus and a scanning electron microscope. In a case
where the electron beam apparatus 1 is used for the X-ray
generation apparatus, the target object 50 is an X-ray generation
target member. In a case where the electron beam apparatus 1 is
used for the scanning electron microscope, the target object 50 is
an inspection object.
[0033] The electron gun 20 includes a flat plate-shaped cathode 21,
a ring-shaped control electrode 22, a ring-shaped anode 23, and an
electrically-heating part 24. The cathode 21 is a generation source
of electrons, and it is possible to use any one of a field emission
type, a schottky type, and a thermionic electron emission type. In
the embodiment, the thermionic electron emission type is used as
the cathode 21. In the embodiment, the cathode 21 does not directly
perform electric heating, and emits thermoelectrons by being heated
up to prescribed temperature through electric heating of the
electrically-heating part 24 which is disposed in the vicinity
thereof. The cathode 21, the control electrode 22, and the anode 23
are arranged and disposed to be separated from each other in an
optical axis direction Z which is a direction along an optical axis
(a dashed line of FIG. 1) of the electron beam. The control
electrode 22 is disposed between the cathode 21 and the anode 23 in
the optical axis direction Z. A negative electric potential is
applied to the control electrode 22 with respect to the cathode 21,
and thus the quantity of electrons emitted from the cathode 21 is
adjusted. The quantity of electrons emitted from the cathode 21
becomes large as an electric potential difference between the
control electrode 22 and the cathode 21 becomes small.
[0034] The cathode 21 includes an emission surface 21a which is a
planar surface capable of emitting the electrons. In the control
electrode 22, a third hole 22a is formed through which the
thermoelectrons emitted from the cathode 21 pass. A shape of the
third hole 22a is, for example, a circle. In the anode 23, a first
hole 23a is formed through which the electron beam passes. A shape
of the first hole 23a is, for example, a circle. In a preferable
example, an area of the emission surface 21a of the cathode 21 is
wider than an opening area B of the third hole 22a formed in an
electrode which is the nearest to the cathode 21, that is, the
control electrode 22 in the embodiment. In a case where the shape
of the third hole 22a is a circle and a radius of the third hole
22a is rb, a calculation formula used to acquire the opening area B
of the third hole 22a is "B=.pi..times.rb2".
[0035] The aperture member 30 is disposed on a side opposite to the
control electrode 22 with respect to the anode 23. The convergence
electrode 40 is disposed on a side opposite to the cathode 21 with
respect to the aperture member 30. In other words, the aperture
member 30 is disposed on a side of the cathode 21 rather than the
convergence electrode 40. In the aperture member 30, an opening 31
is formed which shields some parts of the electron beam that passes
through the anode 23. A shape of the opening 31 is, for example, a
circle. It is possible to set a diameter of the opening 31 to a
random value by taking resolution and light intensity into
consideration. For example, the diameter of the opening 31 is 2
mm.
[0036] The convergence electrode 40 is a final-stage electrode
which is disposed nearest to the target object 50 and which forms
an electric field such that the electron beam converges on a
convergence surface 51 of the target object 50. The convergence
electrode 40 is, for example, a single-hole electrode in which a
second hole 41 is formed in a flat plate. A shape of the second
hole 41 is, for example, a circle. A diameter of the second hole 41
is larger than the diameter of the opening 31 of the aperture
member 30. It is preferable that the diameter of the second hole 41
is determined to a size which does not shade the peripheral parts
of the electron beam that passes through the opening 31 of the
aperture member 30. In an example, the diameter of the second hole
41 is equal to the diameter of the first hole 23a of the anode 23
or is larger than the diameter of the first hole 23a. In another
example, the diameter of the second hole 41 of the convergence
electrode 40 is equal to the diameter of the third hole 22a of the
control electrode 22 or is larger than the diameter of the third
hole 22a. As illustrated in FIG. 1, the respective central axes of
the third hole 22a of the control electrode 22, the first hole 23a
of the anode 23, the opening 31 of the aperture member 30, and the
second hole 41 of the convergence electrode 40 are the same.
[0037] The electron beam apparatus 1 includes a first
electrically-conducting member 70 which causes the aperture member
30 and the convergence electrode 40 to be electrically conducted to
each other in vacuum. The first electrically-conducting member 70
is, for example, a cylindrical member which connects the aperture
member 30 to the convergence electrode 40. In addition, the
electron beam apparatus 1 includes a second electrically-conducting
member 80 which causes the anode 23 and the aperture member 30 to
be electrically conducted to each other in vacuum. The second
electrically-conducting member 80 is, for example, a cylindrical
member which connects the anode 23 to the aperture member 30. In
the embodiment, the anode 23, the aperture member 30, the
convergence electrode 40, the first electrically-conducting member
70, and the second electrically-conducting member 80 are configured
as one member which is formed of the same metal material.
[0038] The control device 60 is electrically connected to the
cathode 21, the control electrode 22, the anode 23, the
electrically-heating part 24, and the target object 50 through
connection members 61, 62, 63, 64, and 65 such as a harness. The
control device 60 is capable of changing electric potentials which
are applied to the cathode 21, the control electrode 22, the anode
23, the electrically-heating part 24, and the target object 50
based on an operation of an operating unit (not shown in the
drawing) provided in the electron beam apparatus 1. Hereinafter, an
aspect of electrification of the cathode 21, the control electrode
22, the anode 23, the electrically-heating part 24, and the target
object 50, which is performed by the control device 60, and an
electron beam, which is irradiated to the convergence surface 51 of
the target object 50 according to the aspect of the
electrification, will be described.
[0039] The control device 60 is configured to heat the cathode 21
by electrifying the electrically-heating part 24 and to cause the
control electrode 22 to apply a negative electric potential with
respect to the electric potential of the cathode 21 and to apply a
positive electric potential with respect to the anode 23. In
addition, the control device 60 is configured to cause the
convergence electrode 40 to apply the negative electric potential
with respect to the electric potential of the target object 50, and
to cause the electrons to be accelerated due to an electric
potential difference between the target object 50 and the
convergence electrode 40. Meanwhile, in the embodiment, as
described above, the electric potential of the anode 23 and the
electric potential of the convergence electrode 40 are the same. In
addition, any one of the cathode 21, the control electrode 22, the
anode 23, and the target object 50 may not be connected to the
control device 60, that is, may be a ground electric potential.
[0040] Due to the electric potential difference, the electrons
emitted from the cathode 21 form the electron beam by being derived
by the anode 23. In a case where the electric potential difference
is generated between the control electrode 22 and the anode 23,
electric fields are formed. A part of an equielectric potential
surface between the control electrode 22 and the anode 23, which is
resulting from the electric potential difference between the
control electrode 22 and the anode 23, is swollen in a curved shape
between the control electrode 22 and the cathode 21 via the third
hole 22a of the control electrode 22, and thus an electro-static
lens used to cause the electron beam to converge is formed. In
addition, in a case where the electric potential difference between
the convergence electrode 40 and the target object 50 is generated,
electric fields are formed. As illustrated in FIG. 2, a part of the
equielectric potential surface between the convergence electrode 40
and the target object 50, which is resulting from the electric
potential difference between the convergence electrode 40 and the
target object 50, is swollen in a curved shape between the
convergence electrode 40 and the aperture member 30 via the second
hole 41 of the convergence electrode 40, and thus the final-stage
electro-static lens used to cause the electron beam to converge on
the convergence surface 51 of the target object 50 is formed.
Meanwhile, in the embodiment, as described above, the electric
potentials of the anode 23, the aperture member 30, and the
convergence electrode 40 are the same, and thus the electron beam
approximately goes straight therebetween.
[0041] As illustrated in FIG. 1, the electron beam converges
between the control electrode 22 and the anode 23, forms a
crossover, and passes through the first hole 23a of the anode 23.
Therefore, a beam diameter of the electron beam, which
approximately goes straight from the anode 23 toward the
convergence electrode 40, becomes wider as being closer to the
convergence electrode 40.
[0042] In both configurations in which the aperture member 30 is
provided like the electron beam apparatus 1 and in which the
aperture member 30 is not provided unlike the electron beam
apparatus 1, the electron beam converges by the final-stage
electro-static lens which is formed by the convergence electrode
40, and the convergence surface 51 of the target object 50 is
irradiated with the electron beam in a state in which the beam
diameter of the electron beam becomes small. However, influence of
spherical aberration on the electron beam, which converges due to
the electric fields formed by the convergence electrode 40, is
large as the beam diameter of the electron beam, which is acquired
before reaching the electric field, is large, and thus it is not
possible to acquire high resolution. In the electron beam apparatus
1 in which the aperture member 30 is provided, in a case where the
electron beam formed by the anode 23 passes through the opening 31
of the aperture member 30, the peripheral parts of the electron
beam are shaded by the aperture member 30, and only the central
part of the electron beam passes through the opening 31. Therefore,
the beam diameter of the electron beam is squeezed by the diameter
of the opening 31, which is smaller than the beam diameter, before
the electron beam passes through the opening 31. Therefore, the
beam diameter of the electron beam, which reaches the final-stage
electro-static lens formed by the convergence electrode 40, becomes
small, with the result that the influence of the spherical
aberration becomes small, and thus it is possible to acquire the
high resolution.
[0043] Subsequently, relation between the anode 23, the aperture
member 30, and the convergence electrode 40 will be described.
Meanwhile, in the description below, distances between respective
members, that is, the anode 23, the aperture member 30, and the
convergence electrode 40 indicate the distances between the
respective members in the optical axis direction Z.
[0044] In the embodiment, as described above, the electric
potentials of the anode 23, the aperture member 30, and the
convergence electrode 40 mutually become the same due to the first
electrically-conducting member 70 and the second
electrically-conducting member 80. Therefore, the anode 23 and the
aperture member 30 may not be insulated for electric discharge
prevention and, in addition, the aperture member 30 and the
convergence electrode 40 may not be insulated for electric
discharge prevention. That is, from a viewpoint of the electric
discharge prevention, it is possible to randomly change the
distance between the anode 23 and the aperture member 30 and the
distance between the aperture member 30 and the convergence
electrode 40, respectively, and it is possible to make the
distances be shorter than an insulation distance which is necessary
for the electric discharge prevention. In the embodiment, the
distance between the anode 23 and the aperture member 30 is longer
than the distance between the aperture member 30 and the
convergence electrode 40, and the aperture member 30 shades the
electron beam at a spot where the electron beam is further
widened.
[0045] In contrast, the distance between the aperture member 30 and
the convergence electrode 40 is restricted as below. As illustrated
in FIG. 3, in a case where the distance between the aperture member
30 and the convergence electrode 40 is short, the respective
equielectric potential surfaces of the electric fields, which leak
from the second hole 41 of the convergence electrode 40 toward the
aperture member 30, become straight line shapes which extend in a
direction along a lower surface of the aperture member 30, and thus
it is difficult that the electron beam converges. In addition, a
part of the equielectric potential surfaces of the electric fields,
which leak from the second hole 41 of the convergence electrode 40
toward the aperture member 30, is changed to a curve by the opening
31 of the aperture member 30. Therefore, the electron beam, which
passes through the opening 31 of the aperture member 30, converges.
A hole diameter of the opening 31 of the aperture member 30 may be
designed by taking only improvement in the resolution according to
reduction in the spherical aberration and balance of the quantity
of electrons which reach the target object 50 into consideration.
However, in a case where an operation as the lens is simultaneously
performed, it is necessary to simultaneously satisfy a restriction
on a lens property, such as a focal distance, and thus there is a
possibility that sufficient resolution is not acquired as a
result.
[0046] Here, setting is performed such that the distance between
the aperture member 30 and the convergence electrode 40 is longer
than a radius of the second hole 41 of the convergence electrode
40. More preferably, setting is performed such that the distance
between the aperture member 30 and the convergence electrode 40 is
equal to or longer than the diameter of the second hole 41 of the
convergence electrode 40. In the embodiment, the distance between
the aperture member 30 and the convergence electrode 40 is longer
than the diameter of the second hole 41 of the convergence
electrode 40. Therefore, as illustrated in FIG. 2, it is difficult
for the final-stage electro-static lens, which is formed by a part
of the equielectric potential surfaces of the electric fields that
leak from the second hole 41 of the convergence electrode 40 toward
the aperture member 30, to be formed in the opening 31 of the
aperture member 30, and thus it is possible to ignore the operation
of the lens in the opening 31. Therefore, it is possible to design
the hole diameter of the opening 31 of the aperture member 30 by
taking only the resolution and light quantity into consideration,
and thus it is easy to acquire desired electron gun
performance.
[0047] According to the electron beam apparatus 1 of the
embodiment, the following advantages are acquired.
[0048] (1) Since the convergence electrode 40 is one single-hole
electrode, it is possible to reduce the size of the convergence
electrode 40 in the optical axis direction Z, compared to a case
where it is assumed that the convergence electrode 40 includes, for
example, a plurality of single-hole electrodes like an einzel lens.
Therefore, it is possible to reduce the size of the electron beam
apparatus 1. In addition, since only one convergence electrode 40
exists as an electrode used to cause the electron beam to converge
between the anode 23 and the target object 50 in the optical axis
direction Z, it is possible to further reduce the size of the
electron beam apparatus 1.
[0049] In addition, the beam diameter of the electron beam emitted
from the anode 23 toward the aperture member 30 becomes wider as
being closer to the aperture member 30. Furthermore, after only the
central part of the electron beam passes through the opening 31 of
the aperture member 30, the electron beam converges by the
convergence electrode 40. Therefore, it is possible to reduce the
influence of the spherical aberration. As described above, since
the aperture member 30 is provided, it is possible to acquire the
high resolution even in a case where the number of electrodes,
which exist between the aperture member 30 and the convergence
surface 51 of the target object 50, is one. Therefore, it is
possible to reduce the size of the electron beam apparatus 1 with
high resolution.
[0050] In addition, in a case where it is assumed that the aperture
member 30 is disposed on a side of the target object 50 rather than
the convergence electrode 40 and an electric potential, which is
the same as that of the target object 50, is applied to the
aperture member 30, it is necessary to shade the peripheral parts
of the electron beam, which converges by the convergence electrode
40, by the aperture member 30 in order to reduce the influence of
the spherical aberration. Therefore, it is necessary to cause the
diameter of the opening 31 to be smaller than the converging
electron beam and to dispose the opening 31 of the aperture member
30 at a central position of the electron beam, and processing
accuracy and positional accuracy should be increased. In addition,
in addition thereto, there is a possibility that addition of a
component, such as provision of a deflector for adjusting a
position of the electron beam, is necessary in order to cause the
electron beam to pass through the opening 31 of the aperture member
30.
[0051] In the embodiment, an electron beam, which is acquired
immediately before converging by the convergence electrode 40, that
is, an electron beam, which converges by the electron gun 20 once
and then the diameter thereof is enlarged, passes through the
opening 31 of the aperture member 30. Therefore, it is possible to
shade the electron beam as much as a desired quantity even in a
case where the processing accuracy and the positional accuracy of
the opening 31 of the aperture member 30 are low. Therefore, it is
possible to easily construct the electron beam apparatus 1. In
addition, it is not necessary to provide the deflector and it is
possible to simplify a configuration of the electron beam apparatus
1.
[0052] (2) In a case where the same electric potential is applied
to the aperture member 30 and the convergence electrode 40, it is
not necessary to provide an insulation distance used to prevent
electric discharge between the convergence electrode 40 and the
aperture member 30. Therefore, it is possible to cause the distance
between the convergence electrode 40 and the aperture member 30 to
be short in the optical axis direction Z. Therefore, it is possible
to reduce the size of the electron beam apparatus 1.
[0053] (3) In a case where the aperture member 30 and the
convergence electrode 40 are electrically conducted to each other
in vacuum by the first electrically-conducting member 70, the
electric potential of the convergence electrode 40 and the electric
potential of the aperture member 30 become the same even though the
number of wires, which are used to electrically connect the control
device 60 to the convergence electrode 40 and the aperture member
30, is reduced. Therefore, it is possible to simplify the
configuration of the electron beam apparatus 1.
[0054] (4) In a case where the distance between the aperture member
30 and the convergence electrode 40 is longer than the radius of
the second hole 41 of the convergence electrode 40, it is possible
to ignore the operation of the electro-static lens due to the
aperture member 30. Therefore, it is possible to design the hole
diameter of the opening 31 of the aperture member 30 by taking only
the resolution and the light quantity into consideration.
[0055] (5) In a case where the same electric potential is applied
to the anode 23 and the aperture member 30, it is not necessary to
provide the insulation distance used to prevent electric discharge
between the anode 23 and the aperture member 30. Therefore, it is
possible to cause the distance between the anode 23 and the
aperture member 30 to be short in the optical axis direction Z.
Therefore, it is possible to reduce the size of the electron beam
apparatus 1.
[0056] (6) In a case where the anode 23 and the aperture member 30
are electrically conducted to each other in vacuum by the second
electrically-conducting member 80, the electric potential of the
anode 23 and the electric potential of the aperture member 30
become the same even though the number of wires, which are used to
electrically connect the control device 60 to the anode 23 and the
aperture member 30, is reduced. Therefore, it is possible to
simplify the configuration of the electron beam apparatus 1.
[0057] Specifically, since the anode 23, the aperture member 30,
and the convergence electrode 40 are electrically conducted to each
other, it is possible to electrically connect the control device 60
to the anode 23, the aperture member 30, and the convergence
electrode 40 through one wire. Therefore, it is possible to further
simplify the configuration of the electron beam apparatus 1.
[0058] (7) It is desired that the cathode 21 is the thermionic
electron emission type. A method for applying heat to the cathode
21 may be a directly-heated type in which electric heating is
directly performed or may be an indirectly-heated type in which the
electrically-heating part 24 that heats the cathode 21 is further
included. In both cases, the cathode 21 is the thermionic electron
emission type, and thus a degree of vacuum in the vacuum chamber 10
may be low compared to, for example, a case where the cathode 21 is
an electric field emission type. Therefore, it is possible to
reduce a size of the vacuum pump 3 used to vacuate the inside of
the vacuum chamber 10.
[0059] (8) In addition, it is desired that a shape of the cathode
21 is a plane. In a case where an area of the emission surface 21a
of the cathode 21 is caused to be larger than an electrode which is
the nearest to the cathode 21, that is, the opening area of the
third hole 22a of the control electrode 22, even though the cathode
21 is deviated from a position, which is preset with respect to the
control electrode 22, in a direction which is orthogonal to the
optical axis direction Z, it is possible to cause the electrons to
pass through the third hole 22a in a state in which an optical axis
of the electron beam emitted from the cathode 21 coincides with a
central axis of the third hole 22a of the control electrode 22. As
above, it is not necessary to perform high-precision adjustment on
the position of the cathode 21 with respect to the control
electrode 22, and thus it is possible to easily construct the
electron beam apparatus 1.
[0060] (9) In addition, from a viewpoint of long term stabilities
of a lifetime and an optical property, it is desired that the
cathode 21 is an impregnated planar thermal cathode. For example,
in a case where a closed-type electron gun which is maintenance
free is applied as the electron gun 20, a replacement frequency of
the closed-type electron gun is low, and thus it is possible to
reduce maintenance costs of the electron beam apparatus 1.
Meanwhile, the closed-type electron gun has a configuration in
which the whole electron gun is exchanged in a case where it is
necessary to exchange a partial component of the electron gun due
to failure or the like.
Modified Example
[0061] The description related to the embodiment is an example of a
form which may be applied to the electron beam apparatus, the X-ray
generation apparatus, and the scanning electron microscope
according to the present invention, and a restriction on the form
is not intended. For example, a modified example of the embodiment
which will be illustrated below and a form, in which at least two
modified examples that do not conflict with each other are
combined, may be applied to the electron beam apparatus, the X-ray
generation apparatus, and the scanning electron microscope
according to the present invention.
[0062] In the embodiment, the resolution is improved in such a way
that the crossover of the electron beam is formed by the control
electrode 22 of the electron gun 20. However, the configuration of
the electron gun 20 is not limited thereto. The control electrode
22 may be omitted from the electron gun 20. Therefore, it is
possible to reduce the size of the electron gun 20.
[0063] In the embodiment, the anode 23, the aperture member 30, and
the convergence electrode 40 are electrically conducted to each
other. However, an electrical configuration of the anode 23, the
aperture member 30, and the convergence electrode 40 is not limited
thereto, and can be changed as in subsequent (A).about.(H).
[0064] (A) As illustrated in FIG. 4, the aperture member 30, the
convergence electrode 40, and the first electrically-conducting
member 70 are integrally formed, and the anode 23 is separately
formed from the aperture member 30, the convergence electrode 40,
and the first electrically-conducting member 70. That is, the
second electrically-conducting member 80 is omitted. The control
device 60 is electrically connected to the anode 23 by, for
example, a connection member 63a, such as harness, and is
electrically connected to the aperture member 30, the convergence
electrode 40, and the first electrically-conducting member 70 by a
connection member 63b. The control device 60 electrifies the anode
23, the aperture member 30, and the convergence electrode 40 such
that the electric potential of the anode 23, the electric potential
of the aperture member 30, and the electric potential of the
convergence electrode 40 become the same. According to the
configuration, the same advantages as in (1).about.(5), (7), (8),
and (9) of the embodiment are acquired.
[0065] (B) As illustrated in FIG. 5, the anode 23, the aperture
member 30, and the convergence electrode 40 are individually
formed, and are not electrically conducted to each other. That is,
the first electrically-conducting member 70 and the second
electrically-conducting member 80 are omitted. The control device
60 is electrically connected to the anode 23, the aperture member
30, and the convergence electrode 40, respectively, via, for
example, connection members 63c, 63d, and 63e such as the harness.
The control device 60 electrifies the anode 23, the aperture member
30, and the convergence electrode 40, respectively, such that the
electric potential of the anode 23, the electric potential of the
aperture member 30, and the electric potential of the convergence
electrode 40 mutually become the same. According to the
configuration, the same advantages as in (1), (2), (4), (5), (7),
(8), and (9) of the embodiment are acquired.
[0066] (C) In the modified example of FIG. 4, the control device 60
generates an electric potential difference between the aperture
member 30 and the anode 23 and an electric potential difference
between the convergence electrode 40 and the anode 23 such that the
electric potentials of the aperture member 30 and the convergence
electrode 40 and the electric potential of the anode 23 become
different from each other. According to the configuration, the same
advantages as in (1).about.(4), (7), (8), and (9) of the embodiment
are acquired.
[0067] (D) In the modified example of FIG. 5, the control device 60
electrifies any one of the aperture member 30, the convergence
electrode 40, and the first electrically-conducting member 70 such
that the electric potential of the aperture member 30 and the
electric potential of the convergence electrode 40 become the same,
and generates an electric potential difference between the anode 23
and the aperture member 30 and an electric potential difference
between the anode 23 and the convergence electrode 40 such that the
electric potential of the aperture member 30 and the electric
potential of the anode 23 become different from each other.
According to the configuration, the same advantages as in (1), (2),
(4), (7), (8), and (9) of the embodiment are acquired.
[0068] (E) In the modified example of FIG. 5, the control device 60
electrifies the anode 23 and the aperture member 30, respectively,
such that the electric potential of the anode 23 and the electric
potential of the aperture member 30 become the same, and generates
the electric potential difference between the aperture member 30
and the convergence electrode 40 such that the electric potential
of the aperture member 30 and the electric potential of the
convergence electrode 40 become different from each other.
According to the configuration, the same advantages as in (1), (4),
(5), (7), (8), and (9) of the embodiment are acquired.
[0069] (F) In the modified example of FIG. 5, the control device 60
generates the electric potential differences between the anode 23,
the aperture member 30, and the convergence electrode 40 such that
electric potentials of the anode 23, the aperture member 30, and
the convergence electrode 40 are different from each other.
According to the configuration, the same advantages as in (1), (4),
(7), (8), and (9) of the embodiment are acquired.
[0070] (G) As illustrated in FIG. 6, the anode 23 and the aperture
member 30 are integrally formed, and the convergence electrode 40
is formed separately from the anode 23 and the aperture member 30.
That is, the first electrically-conducting member 70 is omitted.
The control device 60 is electrically connected to the anode 23 and
the aperture member 30 by, for example, a connection member 63f,
such as harness, and is electrically connected to the convergence
electrode 40 by the connection member 63g. The control device 60
electrifies the anode 23, the aperture member 30, and the
convergence electrode 40 such that the electric potential of the
anode 23, the electric potential of the aperture member 30, and the
electric potential of the convergence electrode 40 become the same.
According to the configuration, the same advantages as in (1), (2),
and (4).about.(9) of the embodiment are acquired.
[0071] (H) In the modified example of FIG. 6, the control device 60
electrifies any one of the anode 23 and the aperture member 30 such
that the electric potentials of the anode 23 and the aperture
member 30 become the same, and generates the electric potential
difference between the anode 23 and the aperture member 30 and the
electric potential difference between the anode 23 and the
convergence electrode 40 such that the electric potentials of the
aperture member 30 and the convergence electrode 40 are different
from each other. According to the configuration, the same
advantages as in (1) and (4).about.(9) of the embodiment are
acquired.
* * * * *